Hello all!
Marble shower wall to base joints appear to have been originally grouted, then later caulked over. I removed the bad caulk and I scored the grout lines. Re-grout or re-caulk over old scored grout lines?

That joint should never have been grouted. It should be caulked.

yeah, just don't score the old grout, remove as much as you can. then caulk it.
i have recently been very impressed with DAP 3.0 caulk. very sticky and very nice..

Why not just caulk on top of the old scored grout lines?
How about Loctite 2-in-1 Seal and Bond Tub and Tile Sealant?



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Only 100% silicone.

Grout cracks with movement. Silicone has the best adhesive qualities, while remaining flexible.

Silicone...OK!
Is it necessary to remove the old scored grout or can I just caulk on top of it?

It's been recommended for a long time to caulk the corners(wall-wall, wall-floor), but it's a know fact that water can get behind wall tile, so if you 100% seal the wall-floor joint, the water can't leak out into the pan/tub. It can build up and flow sideways, exiting outside the shower/tub. Silicone doesn't adhere well to itself, so if you caulk with silicone and have to re-caulk at a later date, good luck getting a good bond without 100% removal of the old silicone. Caulking requires a minimum bond depth to the opposing sides and not applied as a surface smear, so if you want to caulk the joint, you need to remove the old grout.

What's best thing to use to remove grout?

A 5 in 1 tool works to get bigger chunks out. Use the pointy end to get behind the grout and pull.

Be careful not to pry up and chip the marble.

An oscillating tool with a grout blade works great. Or a hand held grout removal blade found in tile section of big box stores works.

Tilers know better than to gout the corners of showers. It's just so much easier to shove grout the the cracks than to come back a day or two later after all the other grout dries and caulk the change of plane corners and joints properly.

Adding to the above posts, be sure you dry out the joint for a few days with a heater and fan to be successful first time. Be careful and do not start a fire with your heater. It could take a couple of hours or more with a hair blow dryer if you go that route. It depends on the size of the opening/crack between the base and the Marble.

I have a 5 in 1, I have an oscillating tool but not sure if I have a grout blade for it, I also have a hand held grout removal blade, which I scored the old grout with because others told me to just caulk over the old scored grout. I'll get in there and try removing the grout with what I have.

As for the caulk, if I need 100% Silicon, I have a couple of questions:
1) @packy has "recently been very impressed with DAP 3.0 caulk"...Anyone have other recommendations?
2) What is best use of my Loctite 2-in-1 Seal and Bond Tub and Tile Sealant?



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100% silicone caulk would be my second choice. just make sure it is mildew resistant.
as for your locktite product... i don't know about you but around my house, caulking never goes to waste..

OK, now I'm confused...You said "DAP 3.0"; the details for DAP 3.0 @ HD say "Caulk Type: Silicone" but 100% silicone caulk would be your second choice...Then, what would be your first choice?

As for my Loctite; it's Latex (Interior/Exterior) that I bought for this project. If Latex is not recommended for this project, what type of projects is Latex used for?

dap 3.0 is not silicone.